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16 Transistor Amp Plans (2SC2879)

543_Dallas said:
Bologna. Those big builds go bad for a lot of reasons. Usually because people are too cheap to buy matching pills, too lazy to match cap values, cheap out on the heatsink, or use a poor layout because it was crammed in too small of a case.

The main reason being the builders don't know what they are doing and just make it look like a davemade or fat boy with some added crap they call improvements. The customer is disappointed and the amp gets sent to another moron for repair. This happens a few times and the amp is finally blown or sold. During this time it was never touched by anyone that understood how the thing works.

All he is doing is building 4 4 transistor amps and using a 4 port splitter and combiner. There's not much loss in these unless the circuit is designed or tuned wrong. I've also saw them built out of 2 transistor modules and with 8 port combiner. If a person can build an amp in identical sections, combine it and has a clue about tuning an LC network it will work very well.

Want to improve efficiency? Retune the circuit so it is optimized for 13.6v and stop copying what davemade NJ was doing over 20 years ago.
Click to expand...

I have never seen one that had the same efficiency as a 1 or 2 transistor build. I have never seen a spliter combiner network set up on a gray market "builder's" amp before! I almost never see proper impedance and proper matching you see them shunting the match to fake a good match etc....Likewise I have never seen a comp box last any time at all. I do not doubt that there might be some decent builders out their but they do a good job staying hide! Usually the only amps I see that are built decently are built by ham's with a background in rf, broadcast, electronic engineering etc....

In fact once you remove all the fake watts that are harmonics you see that the efficiency is insanely low on most of the amps built specifically for the CB market.
 
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Onelasttime said:
I have never seen one that had the same efficiency as a 1 or 2 transistor build. I have never seen a spliter combiner network set up on a gray market "builder's" amp before! I almost never see proper impedance and proper matching you see them shunting the match to fake a good match etc....Likewise I have never seen a comp box last any time at all. I do not doubt that there might be some decent builders out their but they do a good job staying hide! Usually the only amps I see that are built decently are built by ham's with a background in rf, broadcast, electronic engineering etc....

In fact once you remove all the fake watts that are harmonics you see that the efficiency is insanely low on most of the amps built specifically for the CB market.
Click to expand...

Of course you will have less efficiency as you add more components. I'm not saying the splitter and combiner are lossless. I think the problem you have is that you've never had your hands on an amplifier that was working well. You should also keep in mind that efficiency will vary with collector voltage and output levels...then step back and remember what these comp amps were designed for.

I'll give you an opportunity to enlighten me here. What kind of efficiency do you expect to see from a linear amplifier? Linear being the key word and something you would consider to be clean. Also, can you give me an example or schematic where someone is "shunting the match to fake a good match" I'm trying to better understand that concept.

Here you can buy the splitter/ combiner used in Texas Star amplifiers. I'm sure you know they use the same 2 transistor modules and combine them to build larger amplifiers.

https://www.rfparts.com/radioamp-service/texas/texas-combsplit.html

The same concept is used in a 4 pill dave style amp to build a 4 pill out of two 2 pill sections. With this design (the one everyone copies)splitters and combiners are use to put 2 or 4 pill sections together. These circuits are tuned With an LC network. They work very well if they are tuned properly. If you've never saw something like I've deacribed you only work on 2 pills or don't know what you're looking at.

I have comp amps that are decades old with original transistors. The ones being built today probably don't last. Everyone wants to pretend to be a tech/builder. They don't underatand what they are building and cheap out on parts. I heard a rumor that you build amps in plastic boxes. Are you the telestar guy?
 
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543_Dallas said:
Of course you will have less efficiency as you add more components. I'm not saying the splitter and combiner are lossless. I think the problem you have is that you've never had your hands on an amplifier that was working well. You should also keep in mind that efficiency will vary with collector voltage and output levels...then step back and remember what these comp amps were designed for.

I'll give you an opportunity to enlighten me here. What kind of efficiency do you expect to see from a linear amplifier? Linear being the key word and something you would consider to be clean. Also, can you give me an example or schematic where someone is "shunting the match to fake a good match" I'm trying to better understand that concept.

Here you can buy the splitter/ combiner used in Texas Star amplifiers. I'm sure you know they use the same 2 transistor modules and combine them to build larger amplifiers.

https://www.rfparts.com/radioamp-service/texas/texas-combsplit.html

The same concept is used in a 4 pill dave style amp to build a 4 pill out of two 2 pill sections. With this design (the one everyone copies)splitters and combiners are use to put 2 or 4 pill sections together. These circuits are tuned With an LC network. They work very well if they are tuned properly. If you've never saw something like I've deacribed you only work on 2 pills or don't know what you're looking at.

I have comp amps that are decades old with original transistors. The ones being built today probably don't last. Everyone wants to pretend to be a tech/builder. They don't underatand what they are building and cheap out on parts. I heard a rumor that you build amps in plastic boxes. Are you the telestar guy?
Click to expand...
Very serendipitous that you should mention telstar. I'm looking to make the move from sweep tube amps to transistorized ones. Two to be exact. One for my AM station, and the other for my SSB setup. I saw the DX500 telstar amp for the first time last night on eBay.
I asked the telstar seller (whom I believe to be the builder) several questions about his DX500.
The last question being what makes your amp worth (approximately) $350 more than the Texas Star 500V?
After doing a little research, and asking some questions about the 667 and getting the replies I did I believe the 500V will fit my bill.
I'm not shy spending more money if the product is that much better.
The (telstar) guy has yet to get back to me as I asked the question last night. I don't think the sellers answers would've changed my mind although it wouldn't be out of the question for me to spend more if it's worth it.
For $350 more than the 500V the telstar would have to be far superior in the build quality, and a BJ from a brunette BBW when I open the telstar shipping box wouldn't be a bad thing (lol)
I've a feeling you've heard some things about the telstar, and hope you (and other's) will share. The robust heat sink on the telstar looked sufficient, but knowing how hot theses amps get the lack of a fan was the first thing I didn't like about the amp. The plastic case is probably not a good sign either. Your knowledge about amps is obvious. Not to mention so many others on this site who know almost everything if not everything about what makes a four transitor amp worth the $850 price tag or not. Thanks. 73's PS All have an excellent weekend.
Screenshot_20180317-061855.jpg
 
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543_Dallas said:
All the comp amp builders on YouTube shop here. :)

http://www.icamanufacturing.com/

The ebay board is etched but it's not necessary if you use pill strips from ICA. Its actually easier to repair and you dont have to worry about burning the board if you ever have to replace transistors.
Click to expand...

Wow they have everything. Hmmm..... A little 6 pill would be nice.
 
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